An example of this type of jet mill is a fluidized bed type jet mill having a cylindrical container 20 capable of storing raw material powder (hereinbelow simply referred to as “powder”) as an object to be pulverized, wherein a plurality of gas emission nozzles 21 are provided facing each other toward the center from the external peripheral wall of the container, and the powder is carried on emitted gas from the gas emission nozzles 21 to collide with itself and be pulverized, as shown in FIG. 5. A stable performance can be achieved with a jet mill of this configuration, but because the pulverization is performed with powder becoming stagnant inside the apparatus, a problem with this jet mill is that powder remains in the apparatus even after pulverization has ended.
Another type of jet mill is a jet mill such as those shown in Patent Document 1 and Patent Document 2 listed below, wherein powder is made to swirl together with air by emitted gas from the emission nozzles provided to the peripheral wall of a cylindrical pulverization chamber, the powder is pulverized, and the pulverized powder is sent to a classification chamber above the pulverization chamber where it is classified.
In the jet mill disclosed in Patent Document 1, a plurality of gas emission nozzles are attached in a tilted manner with each other in the external peripheral wall of the pulverization chamber, and the powder is carried by emitted gas from the gas emission nozzles and pulverized while swirling at high speed.
In the jet mill disclosed in Patent Document 2, a collision member is provided at a position facing a gas emission port of a gas emission nozzle across a predetermined gap, and the powder is carried by the emitted gas and pulverized by colliding with the collision member.
In the jet mills of Patent Documents 1 and 2, a classification chamber is provided with a classification rotor disposed in the top part of the pulverization chamber, and powder that has been pulverized into the desired grain size is classified and collected.